- 行业: Weather
- Number of terms: 60695
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
A report from an aircraft in flight prepared in conformity with requirements for position and operational and/or meteorological reporting.
Industry:Weather
Maximum legal concentration limits of air pollutants averaged over specified time periods. These are prescriptive. If the actual measured concentration averaged over time exceeds the legal threshold, then the event is called an exceedence. Regulations often allow a limited number of exceedences each year, with fines or penalties imposed for too many exceedences. Regions with too many exceedences are required to develop plans to improve the air quality, for example, by changing automobile fuels and gas-station equipment or increasing the use of mass transportation. In the United States, the standards are called National Ambient Air Quality Standards (NAAQS). Primary standards are designed to protect human health. Secondary standards are designed to protect crops, animals, structures, and commerce. In Canada, these legal thresholds are called National Air-Quality Objectives. Three levels of standards exist within these objectives. In ascending order of concentration limit they are Maximum Desirable Level, Maximum Acceptable Level, and Maximum Tolerable Level. Compare air quality criteria, emission standard, criteria pollutants.
Industry:Weather
Quantitative and qualitative indications of the relationships between exposure to pollutants and effects on human health, animals, plants, and materials. These are descriptive effects of pollution as a function of concentration averaged over various time durations. A time-averaged concentration is used because exposure to a high concentration of pollutants during a short time might have an impact equivalent to an exposure to a lower concentration over a longer time.
Industry:Weather
A colloidal system in which the dispersed phase is composed of either solid or liquid particles, and in which the dispersion medium is some gas, usually air. There is no clear-cut upper limit to the size of particles composing the dispersed phase in an aerosol, but as in all other colloidal systems, it is rather commonly set at 1 μm. Haze, most smokes, and some fogs and clouds may thus be regarded as aerosols. However, it is not good usage to apply the term to ordinary clouds with drops so large as to rule out the usual concept of colloidal stability. It is also poor usage to apply the term to the dispersed particles alone; an aerosol is a system of dispersed phase and dispersing medium taken together. Compare airborne particulates, particles, PM-2. 5, PM-10.
Industry:Weather
Very generally, meteorology as applied to the effects of weather upon aviation.
Industry:Weather
The optical depth due to extinction by the aerosol component of the atmosphere. Aerosol optical depths typically decrease with increasing wavelength and are much smaller for longwave radiation than for shortwave radiation. Values vary widely depending on atmospheric conditions, but are typically in the range 0. 02–0. 2 for visible radiation.
Industry:Weather
The amounts of different size particles of solids or liquids that are suspended in air as an aerosol. Particle size affects scattering of sunlight (see Rayleigh scattering and Mie scattering) that makes blue skies, white clouds, and hazy smog, and that affects visibility. Size affects the nucleation capability of particles to form cloud droplets due to both the curvature effect and the solute effect. Relative amounts of different particle sizes can be used as a tracer for an air mass, such as indicating whether it originated over continents, oceans, urban areas, or rural areas. The total abundance of particles is often proportional to the total number density of cloud droplets, which affects the size to which these droplets can grow and their resulting evolution.
Industry:Weather
A term denoting the physics and chemistry of the upper atmosphere. It is concerned with upper-atmospheric composition (i.e., nature of constituents, density, temperature, etc. ) and chemical reactions.
Industry:Weather
